Aerosol canisters that dispense aerosol foams, such as shaving foam, are known in the art. Typically, shaving foam is dispensed from a pressurized vessel containing the active components of the foam such as soap, oils, surfactants and water, and a hydrocarbon propellant such as propane, butane, isobutene or a mixture thereof. The expelling of the fluid mixture through a dispensing valve and expansion nozzle to atmospheric pressure allows the propellant portion of the dispensed mixture to expand into gas and create foam.
The traditional dispensing system for such an aerosol canister is a normally-closed, push-to-open, release-to-close valve. The user interaction with this valve is inexact, and the system depends on the user to meter and dispense the amount of foam by manually opening the valve until the desired amount of foam is dispensed and then releasing the valve. To add to the imprecision of the dispensed amount of foam, the volume of the foam changes during and after expulsion, making the process of judging “visually” the amount of foam dispensed difficult during the user's interaction with the valve. If the user holds the valve open too long and dispenses too much foam, he is left with the choice of whether to apply all of it too thickly to his face or to separate and discard the excess.
The quality of a shave depends on using the correct amount of shaving foam, as too little does not provide suitable lift of the hairs and lubrication for the razor, and too much can float the blade of the razor or clog a multi-blade razor. The current state of shaving foam dispensing systems is too inexact and user-dependent to provide a metered amount of shaving foam and leads to poor shaves and waste of foam.